Gould, page 448. "It is acceptable to omit a hyphen between a two-syllable
word to save space provided that the word cannot be elided into a single
syllable in error. However, hyphens always clarify text underlay. It is
essential to divide words of more than two sylables with hyphens."

She gives an example of call-ed, where it's often pronounced while singing
as two syllables, but is always a single syllable spoken. Eliding the
hyphen or space would make this distinction difficult to see.